This invention relates to a pallet changer suitable for use with a machine tool.
FMS(flexible manufacturing system) has a machine tool and a pallet changer. The pallet changer exchanges a pallet on a table of the machine tool for another pallet. The conventional pallet changer is a hydraulic cylinder type or a chain type.
In the case of the pallet changer being of a hydraulic cylinder type, a rod of the hydraulic cylinder is extended so that a pallet is settled on the table of the machine tool. After a work on the pallet is machined, the rod is contracted so that the pallet is returned.
In the case of the pallet changer being of a chain type, a plurality of pallets are set to the chain at regular intervals. The chain is driven by a motor so that the pallet is transfered to a pallet changing place near the table of the machine tool.
But, the pallets and the works are considerably heavy. In the case of the pallet changer being of a hydraulic cylinder type, a large hydraulic cylinder is needed. In the case of the pallet changer being of a chain type, a large motor and a big chain are needed. In both cases, the pallet changer is big in size and its construction is complicated.
When the large hydraulic cylinder or the large motor in the pallet changer starts or stops, the pallet changer is shocked. The shock is caused by the inertia of the heavy pallets and the works on the pallets. To avoid the shock, the large hydraulic cylinder and the large motor must be slowly operated.
The object of this invention is to provide an improved pallet changer whose construction is simple. When this pallet changer is used, large cost saving are obtained.
A pallet changer according to this invention, for example, is constructed as follows.
FIG. 1 shows the pallet changer PC comprising a work carrier pallet 4 detachably and movably mounted to a table 2, and another work carrier pallet 14 set at a separate location (pallet table 30 in an embodiment of FIG.2). The table 2 is provided on a support 1 (a support of machine tool in this embodiment) of the pallet changer. The table 2 moves along at least a first axis (the X-axis in this embodiment). The table 2 can reciprocately move along the first axis by means of drive means 3 such as a servomotor. The work carrier pallet 4 is detachably mounted to the table 2, and the work carrier can move on the table 2.
A transfer means 12 transfers the work carrier pallet 4 on the table 2 in a first direction of arrow X1 and a second direction of arrow X2 opposite to the first direction. The pallet 4 moves by a drive power means 3 when the table 2 moves in the first direction of arrow X1 or the second direction of arrow X2.
Pallet 4 is transfered by the drive means 3 only. No other drive means such as a hydraulic cylinder and a motor is required.
The transfer means 12 has a guide body 62, a slide body 69, a first and a second sprocket 64, 65, a chain 66, an engagement means 67 and a mechanism part 100.
The slide body 69 is supported by the guide body 62 fixed to the table 2 and can slide along the first axis. The first sprocket 64 and the second sprocket 65 are provided to one portion and another portion of the slide body 69.
The chain 66 is set between the first and the second sprockets 64, 65.
By means of the engagement means 67, the chain 66 detachably engages the work carrier pallet 4.
When the table 2 moves in the first direction of arrow X1 or in the second direction of arrow X2 by means of drive means 3, the mechanism part 100 drives the chain 66 so that the slide body 69 slides in the first direction of arrow X1 or in the second direction of arrow X2 relative to the table 2. Accordingly, the work carrier pallet 4 slides on the table 2 in the first direction of arrow X1 or in the second direction of arrow X2.
In the pallet changer according to this invention, the pallet moves in the same direction as the table's movement by means of the simple drive means such as the chain and the sprockets, so that a large hydraulic cylinder and a large motor are not required. The construction of the pallet changer according to this invention is simple and the pallet changer is small in size. Using the pallet changer according to this invention, large cost saving can be obtained.